This paper presents an experimental investigation on an important measure of the production inaccuracy, known as overcut, in wire electric discharge machining of WC-Co composite material (with 24% Co). Effect of several process parameters such as pulse on time, pulse off time, peak current and gap voltage on the response (overcut) was evaluated through designed experiments using response surface methodology. It was observed that pulse off time and gap voltage are the significant parameters affecting overcut. The optimized value of overcut was found to be 0.042 mm from the confirmation experiments. An improvement of over 10% was achieved over the best value obtained in experiments through optimization.